A New Start

Ten years after NREL's Aquatic Species Program was shut down, a similar initiative began and now is thriving in its algae research, which includes the evaluation of CO2 recycling.

By Lisa Gibson

Between 1978 and 1996, the Aquatic Species Program at the U.S. DOE's National Renewable Energy Laboratory in Colorado expanded the biofuel portfolio beyond ethanol through its research on freshwater plants, wetland emergents and, of course, algae. That work eventually focused on biodiesel from microalgae, but the entire program was terminated due to low petroleum prices and the projected high costs of algal biofuel production.

But with increases in oil prices, piqued interest in greenhouse gas mitigation and aggressive energy security goals have come a renewed interest in algal biofuel research, and thus the restart of the program, or something similar to it.

A Redesign

The new program is not the Aquatic Species Program, but an unnamed extension of the program formerly known as the ASP. It still focuses on algal biofuel, but takes a biological approach, according to Philip Pienkos, principal research supervisor for NREL.

Following the 2005 release of the Oak Ridge National Laboratory's "Biomass as Feedstock for a Bioenergy and Bioproducts Industry: The Technical Feasibility of a Billion-Ton Annual Supply," commonly called the Billion-Ton Study, NREL reevaluated the potential and uses of terrestrial biomass. The Billion-Ton Study found that an estimated 1.3 billion tons of biomass feedstock could be available countrywide including agricultural residues, forest resources, herbaceous energy crops and woody energy crops. "That really set an upper limit on terrestrial biomass," Pienkos says. "What we didn't anticipate four years ago was the fact that there would be competing uses for that biomass." Especially with the desire to mitigate carbon emissions and an increased portfolio of biofuels, 1 billion tons of terrestrial biomass won't get us far.

"No matter how you slice it, if 1 billion tons of biomass per year is all we can produce, we cannot achieve energy security or complete energy independence based on terrestrial biomass," he says. "So it was that recognition in 2005 that led to the conclusion that everything's changed since the close of the ASP." In addition, NREL realized that there had been changes in basic biotechnology tools in the previous 10 years, in engineering practices and national drivers other than simply economics, he says. "All those things crystallized and led to the conclusion that NREL had to get back into the algae game."

Pienkos and his colleagues spent 2006 trying to understand what the landscape in the algae world looked like and began to reach out to the appropriate partners and funding agencies. "The high-quality feedstocks for biodiesel are less and less available and so there was a ready market for algal lipids as feedstock for biofuels," Pienkos explains. "There was also a need to evaluate the whole carbon dioxide mitigation issue, which is more complex for algae than it is for biofuels with terrestrial crops." From that research, NREL formed the Biofuels Strategic Initiative in 2006, aimed at defining the potential of algae for biofuels production and positioning NREL in algae-derived biofuel research. The initiative also strove to develop partnerships with academia, national labs and the biomass industry, which it succeeded in doing as evidenced by the new algae research collaboration. The first project, a partnership with Chevron to identify and develop algae strains for economic biofuel production started in 2007. "That was really our first focus with the strategic initiative, to reach out to the oil industry because we felt the promise of algal biofuels would be more interesting to them than ethanol," Pienkos says.

The main difference between the new program and the ASP is the funding mechanism, as ASP was funded by the DOE. The research is now being funded by a collaboration of partners and agencies including Chevron, the DOE, the U.S. EPA, the Colorado Center for Biorefining and Biofuels, the Air Force Office of Scientific Research, the International Energy Agency and NREL.

Bioprospecting

As part of the new collaboration, NREL researchers have begun work in bioprospecting, isolating novel strains best suited for biofuel production. "We feel that the overall strain starting point hasn't been necessarily explored to the extent that it needs to," Pienkos says. "As we learn more about what we expect a production strain to do, that makes us smarter and smarter in our strategies to isolate new strains from environmental samples."

The focus hovers around biology for a number of reasons, including the fact that most of the researchers in the collaboration are biologists, basic biology is a crucial element in evaluating the production of algal strains, and it provides the program with the most bang for its buck, Pienkos emphasizes. In addition, the program has tried to leverage only fairly small funding opportunities as the infrastructure for an algal biofuel industry is nonexistent. "We're hampered in moving too far beyond basic biology by our lack of large-scale cultivation abilities and so doing relevant cultivation work; doing extraction, harvesting and conversion to fuel is greatly diminished by the lack of infrastructure here," he laments.

If funding opportunities or a partner for infrastructure expansion were to present itself, Pienkos and the collaboration would consider working on the construction of that infrastructure, but the program has not had success in finding the necessary money thus far. "But we're pretty ambitious," he says. "If the opportunity arises, we'll jump on it." Ultimately, though, the researchers see a need to prioritize. "We are aware of the fact that you can't do everything and it's better to specialize, especially in an area of limited support."

So for now, the team is focusing on research of the laboratory algal strain Chlorella vulgaris. Pienkos says the strain has better production potential than the commonly used chlamydomonas reinhardtii. It also grows well, produces significant fatty acids, and has a large-scale cultivation history for use in dietary supplements. "We feel this is an excellent strain to work with and so we've put together a number of small projects funded by a number of different agencies, including internal funding from NREL, to try to build a comprehensive program with Chlorella," Pienkos says.

Chlorella vulgaris is a freshwater strain, however, which is fine when conducting research in Colorado, but working with saltwater strains is preferable when considering large-scale deployment. "So Chlorella won't necessarily fit the bill for that," Pienkos explains. Chlorella presents other challenges, too, including small cells with tough cell walls, making it difficult to harvest, break and extract. "That's a disadvantage certainly for making progress, but it's an advantage assuming that we're successful in some of our efforts because if we can do it with Chlorella, we can probably do it with other strains as well," Pienkos explains, adding that the new algae program's charter is to accelerate commercialization through translational research.

Eventually, the program will facilitate development of a national algae test bed Pienkos describes as a reasonably scaled production facility with all of the necessary unit operations. With DOE support, NREL has established such pilot test centers for terrestrial biomass in the past and has extensive experience in both thermochemical and biochemical conversion of lignocellulosic material. "We have a dream of building something like that for algae," Pienkos says.

Capitalizing on Carbon

In the meantime, NREL's new algae research collaboration is focusing on a plethora of projects, some using industrial flue gas as a carbon source for algae cultivation. "We have a number of things in our pipeline that involve that," Pienkos says. "It removes some of the uncertainty that you might have if you can use real flue gas or CO2 from other emitters rather than bottled CO2."

A partnership project with the National Research Council Canada's Institute for Marine Biosciences in Halifax, Nova Scotia, is another one of those flue gas projects. The NRC team is working now on the first phase of the research, collecting water samples from areas in Nova Scotia, Alberta, southern Ontario and the Northern U.S. and hoping to come up with algae isolates that can tolerate all the pollutants in the flue gas, while producing large amounts of lipids. Without that tolerance, flue gas will need to be fractioned and cleaned, an expensive process, in order to separate the carbon dioxide from the mix of sulfur dioxide, nitrogen dioxide, carbon monoxide, nitric oxide and other pollutants that can impede algae growth.

"Many of the strains that produce copious amounts of lipids are not very robust and wouldn't tolerate gassing with an industrial flue gas," says Stephen O'Leary, leading research officer with the NRC's algae biofuels program. "So we have to do some amount of searching to find a strain that has those favorable lipid-producing capabilities and yet maintains a robustness such that we can grow it under cultivation conditions where we're introducing an unpurified flue gas." The team hopes to begin construction on a demonstration facility in about 18 months and O'Leary does not expect the strain search to push back that timeline. A number of baseline strains have already been found that would tolerate the gas while producing oil and biomass. "What we're looking for with our environmental screening program are better strains, sort of your champion strains," he says.

Not only do those champion strains need to be flue gas tolerant with high oil production, but also native to the demonstration site, which has not yet been determined. "The reason we're collecting in specific areas is that our goal is to have a portfolio of algae species native to areas where you would consider deploying these technologies, such as industrial areas like southern Ontario and the Alberta oil sands," O'Leary says. The demonstration could be set up at power stations, cement factories, or even breweries. "Our target site is with a coal-fired power generating station," he adds. "That's our major focus."

The team is in negotiations with several possible industrial partners, but O'Leary says it's hard to find one willing to make major in-kind or financial contributions to support and maintain operations, even though most candidates show interest in such a system. "There is a disconnect between interest and implementation," he says, adding that it would require a pile of internal approvals on the plant's part. "We're finding that that can be a long and involved process." He does expect, though, that financial incentives for carbon mitigation soon will push that barrier out of the way. "I don't think that will be an insurmountable hurdle and it's not likely to push back our 18-month timeline," O'Leary says.

Once the demonstration is set up, ideally it will operate for two or three years, but definitely more than one, allowing enough time for research. "We need time to make a scientific evaluation of how well things are working," O'Leary explains. "Because there are not many people working on cultivation on that scale at this time, there are going to be a lot of technical challenges that need to be worked out. It's very unlikely that everything would operate just as we'd hoped it would."

After the demo comes phase three, but O'Leary doesn't yet know what that will bring. "We fully anticipate that we will go beyond the demonstration phase, but until we get that going and have an idea of what the results look like and what the interest is for uptake by industry at that time, we can't make concrete plans beyond that yet, other than the aim of going from demonstration technologies to something that will be taken up commercially and deployed at an industrial level," he says.

"Our interest is two-fold: It's in remediating CO2, or recycling carbon dioxide from industrial emitters, and then converting that carbon dioxide into biomass for sustainable fuel production," O'Leary says. "It really is a project where we want to turn industrial CO2 into a commercially valuable commodity, in this case energy products."

One of the legacies of the ASP is the algae strain isolation work it did and the library of species with high-lipid production it established, O'Leary says. Organizations researching biofuel production still refer to that library as a starting point. "In a way, what we're doing now sort of harkens back to the original Aquatic Species Program," O'Leary says. ‘We're going back out into the environment and to new locations to identify another envelope full of new algae isolates that show the same sort of potential that NREL was looking for in the ASP."